grpc: Add gzip Compression Support

grpc/grpc-client/src/commonMain/kotlin/kotlinx/rpc/grpc/client/ClientInterceptor.kt

@@ -7,7 +7,7 @@ package kotlinx.rpc.grpc.client
 import kotlinx.coroutines.flow.Flow
 import kotlinx.rpc.grpc.GrpcMetadata
 import kotlinx.rpc.grpc.Status
-import kotlinx.rpc.grpc.client.internal.GrpcCallOptions
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 
 /**

grpc/grpc-client/src/commonMain/kotlin/kotlinx/rpc/grpc/client/GrpcCallOptions.kt

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.rpc.grpc.client
+
+import kotlinx.rpc.grpc.GrpcCompression
+import kotlin.time.Duration
+
+/**
+ * The collection of runtime options for a new gRPC call.
+ *
+ * This class allows configuring per-call behavior such as timeouts.
+ */
+public class GrpcCallOptions {
+    /**
+     * The maximum duration to wait for the RPC to complete.
+     *
+     * If set, the RPC will be canceled (with `DEADLINE_EXCEEDED`)
+     * if it does not complete within the specified duration.
+     * The timeout is measured from the moment the call is initiated.
+     * If `null`, no timeout is applied, and the call may run indefinitely.
+     *
+     * The default value is `null`.
+     *
+     * @see kotlin.time.Duration
+     */
+    public var timeout: Duration? = null
+
+    /**
+     * The compression algorithm to use for encoding outgoing messages in this call.
+     *
+     * When set to a value other than [GrpcCompression.None], the client will compress request messages
+     * using the specified algorithm before sending them to the server. The chosen compression algorithm
+     * is communicated to the server via the `grpc-encoding` header.
+     *
+     * ## Default Behavior
+     * Defaults to [GrpcCompression.None], meaning no compression is applied to messages.
+     *
+     * ## Server Compatibility
+     * **Important**: It is the caller's responsibility to ensure the server supports the chosen
+     * compression algorithm. There is no automatic negotiation performed. If the server does not
+     * support the requested compression, the call will fail.
+     *
+     * ## Available Algorithms
+     * - [GrpcCompression.None]: No compression (identity encoding) - **default**
+     * - [GrpcCompression.Gzip]: GZIP compression, widely supported
+     *
+     * @see GrpcCompression
+     */
+    public var compression: GrpcCompression = GrpcCompression.None
+}

grpc/grpc-client/src/commonMain/kotlin/kotlinx/rpc/grpc/client/GrpcClient.kt

@@ -8,7 +8,7 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.rpc.RpcCall
 import kotlinx.rpc.RpcClient
 import kotlinx.rpc.grpc.GrpcMetadata
-import kotlinx.rpc.grpc.client.internal.GrpcCallOptions
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.client.internal.ManagedChannel
 import kotlinx.rpc.grpc.client.internal.ManagedChannelBuilder
 import kotlinx.rpc.grpc.client.internal.bidirectionalStreamingRpc

grpc/grpc-client/src/commonMain/kotlin/kotlinx/rpc/grpc/client/internal/GrpcChannel.kt

@@ -4,6 +4,7 @@
 
 package kotlinx.rpc.grpc.client.internal
 
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.internal.utils.InternalRpcApi
 

grpc/grpc-client/src/commonMain/kotlin/kotlinx/rpc/grpc/client/internal/suspendClientCalls.kt

@@ -22,6 +22,7 @@ import kotlinx.rpc.grpc.Status
 import kotlinx.rpc.grpc.StatusCode
 import kotlinx.rpc.grpc.StatusException
 import kotlinx.rpc.grpc.client.ClientCallScope
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.client.GrpcClient
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.grpc.descriptor.MethodType

grpc/grpc-client/src/jvmMain/kotlin/kotlinx/rpc/grpc/client/internal/GrpcCallOptions.jvm.kt → grpc/grpc-client/src/jvmMain/kotlin/kotlinx/rpc/grpc/client/GrpcCallOptions.jvm.kt

@@ -2,16 +2,21 @@
  * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
-package kotlinx.rpc.grpc.client.internal
+package kotlinx.rpc.grpc.client
 
 import io.grpc.CallOptions
+import kotlinx.rpc.grpc.GrpcCompression
 import kotlinx.rpc.internal.utils.InternalRpcApi
+import java.util.concurrent.TimeUnit
 
 @InternalRpcApi
 public fun GrpcCallOptions.toJvm(): CallOptions {
     var default = CallOptions.DEFAULT
     if (timeout != null) {
-        default = default.withDeadlineAfter(timeout!!.inWholeMilliseconds, java.util.concurrent.TimeUnit.MILLISECONDS)
+        default = default.withDeadlineAfter(timeout!!.inWholeMilliseconds, TimeUnit.MILLISECONDS)
+    }
+    if (compression !is GrpcCompression.None) {
+        default = default.withCompression(compression.name)
     }
     return default
 }

grpc/grpc-client/src/jvmMain/kotlin/kotlinx/rpc/grpc/client/internal/GrpcChannel.jvm.kt

@@ -5,6 +5,8 @@
 package kotlinx.rpc.grpc.client.internal
 
 import io.grpc.Channel
+import kotlinx.rpc.grpc.client.GrpcCallOptions
+import kotlinx.rpc.grpc.client.toJvm
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.internal.utils.InternalRpcApi
 

grpc/grpc-client/src/nativeMain/kotlin/kotlinx/rpc/grpc/client/internal/GrpcCallOptions.native.kt → grpc/grpc-client/src/nativeMain/kotlin/kotlinx/rpc/grpc/client/GrpcCallOptions.native.kt

@@ -4,7 +4,7 @@
 
 @file:OptIn(ExperimentalForeignApi::class)
 
-package kotlinx.rpc.grpc.client.internal
+package kotlinx.rpc.grpc.client
 
 import kotlinx.cinterop.CValue
 import kotlinx.cinterop.ExperimentalForeignApi
@@ -25,4 +25,4 @@ public fun GrpcCallOptions.rawDeadline(): CValue<gpr_timespec> {
             gpr_time_from_millis(it.inWholeMilliseconds, GPR_TIMESPAN)
         )
     } ?: gpr_inf_future(GPR_CLOCK_REALTIME)
-}
+}

grpc/grpc-client/src/nativeMain/kotlin/kotlinx/rpc/grpc/client/internal/GrpcChannel.native.kt

@@ -4,6 +4,7 @@
 
 package kotlinx.rpc.grpc.client.internal
 
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.internal.utils.InternalRpcApi
 

grpc/grpc-client/src/nativeMain/kotlin/kotlinx/rpc/grpc/client/internal/NativeClientCall.kt

@@ -26,6 +26,7 @@ import kotlinx.coroutines.CompletableJob
 import kotlinx.rpc.grpc.GrpcMetadata
 import kotlinx.rpc.grpc.Status
 import kotlinx.rpc.grpc.StatusCode
+import kotlinx.rpc.grpc.append
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.grpc.internal.BatchResult
 import kotlinx.rpc.grpc.internal.CompletionQueue
@@ -36,6 +37,8 @@ import kotlinx.rpc.grpc.internal.toGrpcByteBuffer
 import kotlinx.rpc.grpc.internal.toKotlin
 import kotlinx.rpc.protobuf.input.stream.asInputStream
 import kotlinx.rpc.protobuf.input.stream.asSource
+import kotlinx.rpc.grpc.GrpcCompression
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import libkgrpc.GRPC_OP_RECV_INITIAL_METADATA
 import libkgrpc.GRPC_OP_RECV_MESSAGE
 import libkgrpc.GRPC_OP_RECV_STATUS_ON_CLIENT
@@ -63,6 +66,7 @@ internal class NativeClientCall<Request, Response>(
     private val cq: CompletionQueue,
     internal val raw: CPointer<grpc_call>,
     private val methodDescriptor: MethodDescriptor<Request, Response>,
+    private val callOptions: GrpcCallOptions,
     private val callJob: CompletableJob,
 ) : ClientCall<Request, Response>() {
 
@@ -308,6 +312,16 @@ internal class NativeClientCall<Request, Response>(
         val opsNum = 2uL
         val ops = arena.allocArray<grpc_op>(opsNum.convert())
 
+        // add compression algorithm to the call metadata.
+        // the gRPC core will read the header and perform the compression (compression_filter.cc).
+        if (callOptions.compression !is GrpcCompression.None) {
+            if (callOptions.compression !is GrpcCompression.Gzip) {
+                // to match the behavior of grpc-java, we throw an error if the compression algorithm is not supported.
+                cancelInternal(grpc_status_code.GRPC_STATUS_INTERNAL, "Unable to find compressor by name ${callOptions.compression.name}")
+            }
+            headers.append("grpc-internal-encoding-request", callOptions.compression.name)
+        }
+
         // turn given headers into a grpc_metadata_array.
         val sendInitialMetadata: grpc_metadata_array = with(headers) {
             arena.allocRawGrpcMetadata()
@@ -460,4 +474,3 @@ internal class NativeClientCall<Request, Response>(
         }
     }
 }
-

grpc/grpc-client/src/nativeMain/kotlin/kotlinx/rpc/grpc/client/internal/NativeManagedChannel.kt

@@ -20,6 +20,8 @@ import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.cancelChildren
 import kotlinx.coroutines.withTimeoutOrNull
 import kotlinx.rpc.grpc.client.ClientCredentials
+import kotlinx.rpc.grpc.client.GrpcCallOptions
+import kotlinx.rpc.grpc.client.rawDeadline
 import kotlinx.rpc.grpc.descriptor.MethodDescriptor
 import kotlinx.rpc.grpc.internal.CompletionQueue
 import kotlinx.rpc.grpc.internal.GrpcRuntime
@@ -163,7 +165,7 @@ internal class NativeManagedChannel(
         grpc_slice_unref(methodNameSlice)
 
         return NativeClientCall(
-            cq, rawCall, methodDescriptor, callJob
+            cq, rawCall, methodDescriptor, callOptions, callJob
         )
     }
 

grpc/grpc-core/src/commonMain/kotlin/kotlinx/rpc/grpc/GrpcCompression.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.rpc.grpc
+
+/**
+ * Represents a compression algorithm for gRPC message encoding.
+ *
+ * Compression can be applied to gRPC messages to reduce bandwidth usage during transmission.
+ *
+ * ## Supported Algorithms
+ * - [None] (identity): No compression is applied.
+ * - [Gzip]: GZIP compression algorithm, widely supported and provides good compression ratios.
+ *
+ * This interface is not meant to be implemented by users.
+ *
+ * @property name The compression algorithm identifier sent in the `grpc-encoding` header.
+ *
+ * @see kotlinx.rpc.grpc.client.GrpcCallOptions.compression
+ * @see GrpcCompression.None
+ * @see GrpcCompression.Gzip
+ */
+@OptIn(ExperimentalSubclassOptIn::class)
+@SubclassOptInRequired
+public interface GrpcCompression {
+
+    /**
+     * The name of the compression algorithm as it appears in the `grpc-encoding` header.
+     */
+    public val name: String
+
+    /**
+     * Represents no compression (identity encoding).
+     *
+     * This is the default compression setting. When used, messages are transmitted without
+     * any compression applied.
+     */
+    public object None : GrpcCompression {
+        override val name: String = "identity"
+    }
+
+    /**
+     * Represents GZIP compression.
+     *
+     * GZIP is a widely supported compression algorithm that provides good compression ratios
+     * for most data types.
+     *
+     * **Note**: Ensure the server supports GZIP compression before using this option,
+     * as the call will fail if the server cannot handle the requested compression algorithm.
+     */
+    public object Gzip : GrpcCompression {
+        override val name: String = "gzip"
+    }
+}

grpc/grpc-core/src/commonTest/kotlin/kotlinx/rpc/grpc/test/CoreClientTest.kt

@@ -13,7 +13,7 @@ import kotlinx.rpc.grpc.Status
 import kotlinx.rpc.grpc.StatusCode
 import kotlinx.rpc.grpc.client.createInsecureClientCredentials
 import kotlinx.rpc.grpc.client.internal.ClientCall
-import kotlinx.rpc.grpc.client.internal.GrpcCallOptions
+import kotlinx.rpc.grpc.client.GrpcCallOptions
 import kotlinx.rpc.grpc.client.internal.ManagedChannel
 import kotlinx.rpc.grpc.client.internal.ManagedChannelBuilder
 import kotlinx.rpc.grpc.client.internal.buildChannel